c - C中数据类型的最小值和最大值

Question

在 C 中确定数据类型(即 int、char.等)的最小值和最大值的函数是什么？

Answer 1

您需要使用 limits.h它提供以下常量(根据链接引用):

SCHAR_MIN      : minimum value for a signed char
SCHAR_MAX      : maximum value for a signed char
UCHAR_MAX      : maximum value for an unsigned char
CHAR_MIN       : minimum value for a char
CHAR_MAX       : maximum value for a char
SHRT_MIN       : minimum value for a short
SHRT_MAX       : maximum value for a short
USHRT_MAX      : maximum value for an unsigned short
INT_MIN        : minimum value for an int
INT_MAX        : maximum value for an int
UINT_MAX       : maximum value for an unsigned int
LONG_MIN       : minimum value for a long
LONG_MAX       : maximum value for a long
ULONG_MAX      : maximum value for an unsigned long
LLONG_MIN      : minimum value for a long long
LLONG_MAX      : maximum value for a long long
ULLONG_MAX     : maximum value for an unsigned long long
PTRDIFF_MIN    : minimum value of ptrdiff_t
PTRDIFF_MAX    : maximum value of ptrdiff_t
SIZE_MAX       : maximum value of size_t
SIG_ATOMIC_MIN : minimum value of sig_atomic_t
SIG_ATOMIC_MAX : maximum value of sig_atomic_t
WINT_MIN       : minimum value of wint_t
WINT_MAX       : maximum value of wint_t
WCHAR_MIN      : minimum value of wchar_t
WCHAR_MAX      : maximum value of wchar_t
CHAR_BIT       : number of bits in a char
MB_LEN_MAX     : maximum length of a multibyte character in bytes

U*_MIN 由于显而易见的原因被省略(任何无符号类型的最小值为 0)。

同样float.h为 float 和 double 类型提供限制:

FLT_MIN    : smallest normalised positive value of a float
FLT_MAX    : largest positive finite value of a float
DBL_MIN    : smallest normalised positive value of a double
DBL_MAX    : largest positive finite value of a double
LDBL_MIN   : smallest normalised positive value of a long double
LDBL_MAX   : largest positive finite value of a long double
FLT_DIG    : the number of decimal digits guaranteed to be preserved converting from text to float and back to text
DBL_DIG    : the number of decimal digits guaranteed to be preserved converting from text to double and back to text
LDBL_DIG   : the number of decimal digits guaranteed to be preserved converting from text to long double and back to text

浮点类型围绕零对称，因此最负的有限数是最正的有限数的负数 - 例如 float 范围从 -FLT_MAX 到 FLT_MAX。

请注意，浮点类型只能精确表示其范围内的少量有限数量的值。随着存储的绝对值变大，可以精确表示的相邻数字之间的间距也变大。